Performance monitoring: How are you feeling right now?

Statistical analysis is the biggest value-add that RFMS brings to the RF Management Suite. As described in part 3 of this series, the MSP can collect performance data from all devices throughout an enterprise WLAN, but it defers to RFMS to make sense of that data. RFMS steps up to the plate by delivering over 200 statistics that can help administrators visualize and optimize WLAN availability and performance.

In a stand-alone deployment, RFMS Statistics start with an All Sites summary table that lists per-Site device/radio up/down counts, active MU and rogue AP counts, and average RF signal strength. This table is accompanied by a few overall summary charts, such as the percentage of sites falling into five RFMS-defined RF coverage categories.

Detailed stats begin at the individual Site level, reached by selecting a node on the Site tree (as when RFMS is launched from the MSP). Here, extensive per-Site stats are organized into two categories: Network Utilization and Infrastructure.

For example, KPIs weight RF coverage, load balancing, security, redundancy, and network utilization on a "spider web" that plots current versus best value for each. The KPI page also displays average retries and bitspeed per radio and MU, presented as bar graphs (covering the last 30 seconds and hour) or trend lines (showing how polled values changed over time).

These and other utilization graphs are intended to convey network health at-a-glance, giving operators the ability to quickly determine if and where performance problems lie, backed by raw data. But statseven roll-up stats like KPIsare not always intuitive. RFMS addresses this by providing an "expert view" for each network utilization page that suggests potential problems and resolutions.

Figure 4.8  Signal Strength Graph and corresponding Expert View

These RFMS graphs and expert views offer a lot of promise. Frankly, we could not judge stat accuracythese variables change too quickly. But we did try to use network utilization pages to spot and diagnose simulated problems. Usually, RFMS stats reflected the problems we (intentionally) caused. However, we did not gain as much insight as we'd hoped from expert viewsor mouse-over "quick tips." These more advanced outputs will no doubt be augmented as RFMS matures.

Finally, Infrastructure pages drill into data collected about individual entities (APs, switches, radios, MUs, and SSIDs) within a single Site.

For example, Access Point graphs plot signal, noise, utilization, and LAN/WAN packets for any AP-5131 or AP-5181. These graphs are displayed by selecting a desired AP from the table summarizing all APs discovered at (or created for) a single Site. If you don't immediately see the AP you're looking for, a search tool can be used to find it by name, IP address, or MAC address. Once you've spotted a potential problem, further detail can be obtained in two ways: (1) by using the Raw Data panel to view recent stats or (2) by connecting to the AP itself via Telnet or HTTP. A nice addition here would be a button that brings you back to the corresponding device in the MSP console.

A conceptually similar Infrastructure panel plots signal, noise, utilization, and bitspeed for any WS-2000, 5100, or 7000 switchbut RFMS does not show stats for individual thin APs. If you want to drill down further, go to the Radios panel, which displays similar stats for each radio (whether housed by a thick or thin AP). Or ask RFMS to slice the pie differently, displaying stats for each SSID (WLAN) at the selected Site.

These are real-time graphs, displayed for entities that are currently active, plotted over 30-second and one-hour look-back periods. As a result, stats can only be seen for MUs that are actively associatedor for SSIDs currently carrying traffic. This approach is sensible for dynamic entitiesjust think of how many MUs would accumulate over time! But it did complicate troubleshooting for disconnected thin APs and even one switch that went AWOL due to a firmware bug. Overall, we found the currency of these pages very helpful, but we also like the ability to zoom out to longer periods and/or adjust graph refresh rates.

Reporting: How have you been?

Even though RFMS tends to "live in the moment," there are a couple of ways that you can record this information for posterity. First, many of the individual tables displayed by RFMS can be exported to .CSV files. Second, RFMS can generate six canned PDF reports on demand: Service Interruptions, Planning, Security, AP Utilization, KPI, and Signal Strength.

For example, the Service Interruptions report identifies the most recent off-line event for each device, including reboots, excessive retries when attempting to poll the device, or inability to reach the device. The Planning report prints a Site floor plan, including configured device locations. The Security report enumerates all previously-detected rogue MUs and rogue APs. And so on.

Figure 4.11  Example RFMS Reports

RFMS reports are not as visual as RFMS graphsin fact, the ability to freeze and export or print graphs would be a nice addition. More importantly, RFMS reports are not really historical performance reportsthey are raw data tables, printed to PDF instead of being exported to CSV. RFMS has access to historical data; we would love to print the same report for last week or last month, so that we could compare past and current stats.

Conclusion

We found RFMSv2.0 to be a highly visual WLAN monitoring and troubleshooting tool, focused on centralized analysis and display of near-real-time status and performance. Help desk staff and administrators for Motorola WLANs can certainly benefit from RFMSv2.0 today. But expert views hint at how RFMS could mature into a more powerful tool over time.

On the other hand, multiple ways of accomplishing the same tasks make RFMS more complexexamples include standard vs. enhanced rogue detection and manual vs. automated vs. imported AP placement. Some older methods could potentially be retired if RFMS can depend more heavily on other RF Management Suite products to perform functions, such as planning and locationing.

As discussed in part 1, the RF Management Suite touches on all aspects of wireless management, from planning to maintenance, from fault surveillance to security and performance monitoring. Now that these pieces live under one roof, Motorola can start to polish the seams that are visible between products originally developed by Motorola, Symbol, Wireless Valley, and AirDefense. In fact, after we completed our tests, Motorola released an updated RF Management Suite v3 with tighter WIPS integration. Clearly, this entire suite will continue to evolveincluding support for new Motorola 802.11n devices and incorporation of wireless technologies that go beyond Wi-Fi.

Lisa Phifer owns Core Competence, a consulting firm focused on business use of emerging network and security technologies.